Abstract
In a screen for suppressors of npr1-5-based salicylic acid (SA) insensitivity, we isolated a semidominant gain-of-function mutation, designated ssi4, that confers constitutive expression of several PR (pathogenesis-related) genes, induces SA accumulation, triggers programmed cell death, and enhances resistance to bacterial and oomycete pathogens. Through map-based cloning, ssi4 was identified and found to encode a putative protein belonging to the TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leu-Rich Repeat) class of R (resistance) proteins. Comparison between ssi4 and the corresponding wild-type sequence revealed a single amino acid substitution in the NBS. Epistasis analysis indicated that SA and EDS1 are required for ssi4-induced PR-1 expression and enhanced disease resistance; they also are required for the increased accumulation of SSI4 and EDS1 transcripts detected in the ssi4 mutant. Although high levels of ssi4 transcripts correlate with the appearance of the mutant phenotype, overexpression of the wild-type SSI4 gene failed to induce stunting, spontaneous lesion formation, or increased PR-1 expression associated with the ssi4 mutation. Thus, the ssi4 phenotype does not appear to be caused by overexpression of this R gene; rather, we propose that the NBS substitution generates a constitutively activated R protein. Furthermore, because SA treatment induced the expression of SSI4 and the closely related TIR-NBS-LRR genes RPP1 and RPS4 but had little effect on the expression of the coiled-coil NBS-LRR genes RPM1 and RPS2, we suggest that SA not only functions as a critical signal for downstream resistance events but also upregulates the expression of certain R genes.
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Claims 15
Claim · model-written summary
The ssi4 mutation caused constitutive PR gene expression.
- Taxon
- Arabidopsis
Arabidopsist0 - Treatment
- gain-of-function mutatione0
- Gene
- ssi4e0
- Outcome
- constitutive expression of several PR (pathogenesis-related) genese0
- Direction
- constitutivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a semidominant gain-of-function mutation, designated ssi4, that confers constitutive expression of several PR (pathogenesis-related) genes”
t0“Arabidopsis”
Claim · model-written summary
The ssi4 mutation induced salicylic acid accumulation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ssi4, that confers constitutive expression of several PR (pathogenesis-related) genes, induces SA accumulation”
t0“Arabidopsis”
Claim · model-written summary
The ssi4 mutation triggered programmed cell death.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- programmed cell deathe0
Not reportedTreatmentComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“triggers programmed cell death”
t0“Arabidopsis”
Claim · model-written summary
The ssi4 mutation enhanced resistance to bacterial and oomycete pathogens.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- resistance to bacterial and oomycete pathogense0
- Direction
- enhancese0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhances resistance to bacterial and oomycete pathogens”
t0“Arabidopsis”
Claim · model-written summary
Map-based cloning identified ssi4 as encoding a putative TIR-NBS-LRR resistance protein.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ssi4e0
- Outcome
- putative protein belonging to the TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leu-Rich Repeat) class of R (resistance) proteinse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Through map-based cloning, ssi4 was identified and found to encode a putative protein belonging to the TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leu-Rich Repeat) class of R (resistance) proteins.”
t0“Arabidopsis”
Claim · model-written summary
The ssi4 sequence had one amino acid substitution in the NBS compared with wild type.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ssi4e0
- Outcome
- single amino acid substitution in the NBSe0
- Comparator
- corresponding wild-type sequencee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison between ssi4 and the corresponding wild-type sequence revealed a single amino acid substitution in the NBS.”
t0“Arabidopsis”
Claim · model-written summary
SA and EDS1 were required for ssi4-induced PR-1 expression.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- EDS1e0
- Compound
- SAe0
- Outcome
- ssi4-induced PR-1 expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Epistasis analysis indicated that SA and EDS1 are required for ssi4-induced PR-1 expression and enhanced disease resistance”
t0“Arabidopsis”
Claim · model-written summary
SA and EDS1 were required for enhanced disease resistance in ssi4.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- EDS1e0
- Compound
- SAe0
- Outcome
- enhanced disease resistancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Epistasis analysis indicated that SA and EDS1 are required for ssi4-induced PR-1 expression and enhanced disease resistance”
t0“Arabidopsis”
Claim · model-written summary
SA and EDS1 were required for increased SSI4 and EDS1 transcript accumulation in ssi4.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- SSI4 and EDS1e0
- Outcome
- increased accumulation of SSI4 and EDS1 transcriptse0
- Qualifier
- ssi4 mutante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“they also are required for the increased accumulation of SSI4 and EDS1 transcripts detected in the ssi4 mutant.”
t0“Arabidopsis”
Claim · model-written summary
High ssi4 transcript levels correlated with the mutant phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ssi4e0
- Outcome
- appearance of the mutant phenotypee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high levels of ssi4 transcripts correlate with the appearance of the mutant phenotype”
t0“Arabidopsis”
Claim · model-written summary
Wild-type SSI4 overexpression did not induce stunting, spontaneous lesions, or increased PR-1 expression.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- overexpression of the wild-type SSI4 genee0
- Gene
- SSI4e0
- Outcome
- stunting, spontaneous lesion formation, or increased PR-1 expressione0
- Direction
- failed to inducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overexpression of the wild-type SSI4 gene failed to induce stunting, spontaneous lesion formation, or increased PR-1 expression associated with the ssi4 mutation.”
t0“Arabidopsis”
Claim · model-written summary
The authors propose that the NBS substitution constitutively activates the R protein.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- R proteine0
- Outcome
- constitutively activated R proteine0
- Qualifier
- NBS substitutione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we propose that the NBS substitution generates a constitutively activated R protein.”
t0“Arabidopsis”
Claim · model-written summary
SA treatment induced SSI4, RPP1, and RPS4 expression.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- SA treatmente0
- Gene
- SSI4 and the closely related TIR-NBS-LRR genes RPP1 and RPS4e0
- Outcome
- expression of SSI4 and the closely related TIR-NBS-LRR genes RPP1 and RPS4e0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SA treatment induced the expression of SSI4 and the closely related TIR-NBS-LRR genes RPP1 and RPS4”
t0“Arabidopsis”
Claim · model-written summary
SA treatment had little effect on RPM1 and RPS2 expression.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- RPM1 and RPS2e0
- Outcome
- expression of the coiled-coil NBS-LRR genes RPM1 and RPS2e0
- Direction
- little effecte0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“had little effect on the expression of the coiled-coil NBS-LRR genes RPM1 and RPS2”
t0“Arabidopsis”
Claim · model-written summary
The authors suggest that SA upregulates certain resistance genes.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- SAe0
- Outcome
- expression of certain R genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SA not only functions as a critical signal for downstream resistance events but also upregulates the expression of certain R genes.”
t0“Arabidopsis”
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